1. Field of the Invention
The present invention relates to a suspension system for an automotive vehicle. More specifically, the invention relates to a stabilizing device for use with a suspension system for an automotive vehicle, particularly to a stabilizing device applied to such a vehicle having a rear coil-spring suspension.
2. Description of the Prior Art
As is well known to those skilled in the art, a vehicle body or vehicle chassis is suspended on front and rear vehicle wheel axles through a front and rear suspension system. One such suspension system is a coil spring suspension which includes shock absorbing means and suspension arms. The suspension arms comprise upper and lower control arms each of which has one end connected to the vehicle body or chassis and the other end connected to an axle housing for supporting the axle below the vehicle body. The shock absorbing means includes a coil spring and a shock absorber and is interposed between the vehicle body and the axle housing. The shock absorber acts to absorb road shock applied to the vehicle in the vertical direction by compressing and expanding. However, sufficient flexibility is required for the comfort of those riding the vehicle, and also sufficient stiffness in the suspension is required to effectively absorb road shocks to prevent the vehicle from rough riding. Since the shock absorber means directly connects the vehicle body and the axle housing and since if it is too stiff it will transmit road shock so as not to provide a smooth ride, the stiffness of the shock absorbers has conventionally been limited so as not to degrade the comfort of riding. In consideration of the comfort of passengers in the vehicle, the power of a coil-spring rear suspension is limited to a lower range than that required to stabilize the vehicle body. In practice, the power of a rear suspension is limited to a range of a maximum of 30 kg/0.1 m/sec. Thus, the suspension system actually supplies insufficient stabilizing force for the vehicle.
For the purpose of assisting the suspension to stabilize the vehicle, there are provided resilient bushings including shock absorbing rubber members at the various joints, such as the joints between the upper and lower arms and the chassis or vehicle body. The bushings are also intended to absorb vibrations of the axle housing which otherwise create uncomfortable noise. However, the ability of bushings to absorb road shocks exerted on the vehicle and vibrations of the axle housing is limited by the required strength of suspension for the vehicle. Therefore, such bushings are inadequate to simultaneously stabilize the vehicle and to absorb the vibrations of the axle housing.
In the prior art, there have been suspension systems having shock absorbing means cooperating with the vehicle suspension for absorbing road shocks. As such an absorbing means is directly connected to the vehicle chassis or body at least at one end thereof, it has also been limited in the stabilizing force it can provide. This may cause inadequacy of stability for the vehicle suspension system relative to that required. Further, when the vehicle is rapidly decelerated during driving, inertia and reaction thereto will be applied to the vehicle in the forward and backward directions. Since a conventional vehicle suspension is provided for the purpose of absorbing forces and stabilizing the vehicle in response to vertical forces applied to the vehicle, it cannot absorb forces applied in the forward and backward directions. The vehicle may also be subject to forces in the lateral direction which are caused when the vehicle corners at high speed or travels around sharp corners. For such forces applied to the vehicle in the forward or backward direction or lateral direction, the conventional suspension may not effectively stabilize the vehicle. In such a case, mere bushings will not be sufficient to absorb the force.
The present invention is to provide an improved suspension system which can solve the above-mentioned difficulties and disadvantages of a conventional vehicle suspension system.